The use of cuvettes or like receptacles in manual or automated medical diagnostic tests is well known. In a manual test, such as one which measures the amount of radiant energy absorbed by a test specimen, a technician dispenses precise quantities of a particular reagent and diluent into the cuvette. The contents are mixed and the amount of radiant energy absorbed by the mixture is measured. This provides the technician with an initial, baseline reading. Subsequently, the test specimen is introduced into the mixture and the test is conducted again. The results of the baseline test and the test incorporating the specimen are then compared and the amount of absorbed radiant energy attributable to the sample is determined. The accuracy of the test results is largely dependent on the precision with which the technician measures and dispenses the reagent and diluent into the cuvette.
To reduce the potential for human error, automated test equipment have employed cuvettes including one chamber wherein the reagent is prepackaged and another chamber for retaining the test specimen. The cuvettes also include a cover which is movable between an open position for accessing the chambers and a closed position overlying and enclosing the chambers. A post is provided on the cover for breaking a frangible surface in the chamber holding the specimen. During operation of the test equipment, the cover is moved from the open to the closed position causing the post to engage and break the frangible surface, and thereby allow the test specimen to mix with the reagent.
The automated test equipment often incorporates a carousel or like rotatably-driven carriage having individual receptacles for retaining a plurality of cuvettes. During a test, the carousel rotates each cuvette into a test position and a plunger or other device engages the cover of the cuvette, moving it from the open to the closed position. A difficulty sometimes occurs whereby the movement of the plunger causes the cover of the cuvette to be skewed relative to the chamber retaining the test specimen as the cover is moved from the open to the closed position. This in turn can cause the post to be forced against the edge of the chamber holding the test sample thereby preventing the cover from closing and the test specimen from mixing with the reagent.
Accordingly, it is an object of the present invention to provide a cuvette that overcomes the above-described drawbacks and disadvantages of the prior art.